The United States played a pivotal role in the establishment of NATO (North Atlantic Treaty Organization) in 1949. As one of the founding members, the U.S. sought to create a collective defense system to deter Soviet expansion during the early Cold War. The U.S. provided military leadership, financial resources, and strategic guidance, emphasizing the principle that an attack on one member would be considered an attack on all. NATO solidified Western alliances, enhanced military cooperation among member countries, and served as a counterbalance to the influence of the Soviet Union, marking a significant development in international relations during the Cold War.